Air Compressor Troubleshooting Guide

 Passing Excessive Oil 1 2 3 4 5 6 7 8
 Knock or Rattle 9 10 11 12 13      
 Slow Air Buildup 1 6 8 9 10 14 15 16
 Will Not Unload 15 17 18          
 Excessive Load/Unload Cycling 15 17 19 20        
 Runs Hot 9 16 20 21 22 23 24 25


1  Restricted air intake. Change air filter element, local or engine. Kinked air hose. Vacuum from engine   turbocharger when the compressor air intake is hooked to the engine air intake. Use inlet check valve   assembly.
2  Restricted or kinked oil return line. Return line size must be a minimum of 5/8” O.D. Check for silicone   buildup in the drain hole. Excessive engine rotation may require a bottom drain on the compressor.
3  Poorly filtered air. Check for defective intake components.
4  Improper cooling. Restricted water flow, maximum coolant flow plumbed into the block and out the head   (opposite sides)
5  No air dryer in the system. Drain reservoir tanks daily.
6  Excessive duty cycle. Check for system leakage, inadequate compressor size for vehicle application.
7  Excessive engine oil pressure and or crankcase pressure.
8  Compressor worn out or defective
9  Restricted air discharge
10  Loose pulley or worn drive gear components
11  Lack of lubrication has created excessive bearing clearances.
12  Mounting bracket vibration
13  Carbon formation on the top of piston/bottom of cylinder head.
14  Air dryer purge valve stuck open.
15  Defective unloader mechanism and/or governor
16  Braided discharge line heat fatigued. Check with a soap solution.
17  Discharge valve leakage. Excessive system leakage.
18  Governor reservoir or unloader line is restricted.
19  Reservoir volume reduced. Drain water from system.
20  Brakes out of adjustment. Increased volume usage.
21  Improper cooling. Restricted water flow, maximum coolant flow plumbed into block and out of the head   (opposite sides).
22  Insufficient air blast cooling. Clean cooling fans.
23  Carbon comes from heat. Look for restriction. Early engines did not utilize inner coolers. Compressor inlet   turbocharged to elevate temperatures.
24  Compressor is turbocharged at temperatures/pressures and RPM above acceptable limitations. Consult   manufacture for parameters.
25  Brand of multi-grade motor oil; some oil brands allow carbon and varnish formation at lower  temperatures.